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ARS Home » Midwest Area » Columbia, Missouri » Plant Genetics Research » Research » Publications at this Location » Publication #65966
Title: PHYSICAL AND GENETIC MAPPING OF CHROMOSOME 9S IN MAIZE USING MUTATIONS WITHTERMINAL DEFICIENCIES

Author
item CHAO, SHIAOMAN - UNVI OF MISSOURI
item GARDINER, JACK - UNIV OF IOWA
item MELIA-HANCOCK, SUSAN - UNIV OF MISSOURI
item Coe Jr, Edward

Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Two questions were posed in this study: (1) Is a chromosome map derived by genetic (recombinational) analysis consistent with one derived by physical (deficiency) analysis? (2) When chromosomes are broken and the ends are 'healed' by recovery processes in the cell, is it possible to identify the location and distance of the healed end from genes and DNA markers in the chromosome? By combining deficiencies of different lengths starting from the end of chromosome 9 of corn (generated by breakage of chromosomes), with determination of the genes and DNA segments that are lost, and with physical methods measuring the size of segments from the broken end to marked points, both questions were answered affirmatively. With this information, the techniques of genetic mapping are reinforced; the process of healing of chromosomes can be trusted to stabilize chromosomes (for example, in genetic engineering work); and further methods are made available for determination of genome location of newly found genes.

Technical Abstract: Two questions were posed in this study: (1) Is a chromosome map derived by genetic (recombinational) analysis consistent with one derived by physical (deficiency) analysis? (2) When chromosomes are broken and the ends are 'healed' by recovery processes in the cell, is it possible to identify the location and distance of the healed end from genes and DNA markers in the chromosome? Deletion mapping was employed to determine the physical order of five morphological variants, pyd1, yg2, wd1, v28 and v31, with respect to DNA markers located at the distal end of chromosome 9S in maize. The genetic materials used were a series of terminal-deficiency mutants, newly derived with McClintock's original stocks developed in the 1940's, via breakage-fusion-bridge cycles. A combined physical map and genetic map has been constructed based on data gathered from both genetic complementation tests and analysis with restriction fragment length polymorphisms (RFLPs) and disappearance of probed sequences. The location of v31 in relation to RFLP markers was also determined by interval mapping. The physical distance between the healed telomeric end and the most distal RFLP marker in two terminal-deficiency lines was established by using pulsed-field gel electrophoresis and verified by Bal31 digestion of the ends of the chromosome. The results from this study set a foundation for studies on the mechanism of healing of broken chromosome ends in higher plants.